The present invention relates to methods and apparatus for biodegradation of pollutants in fluid bodies. Aeration of fluids will lead to the growth of microorganisms such as bacteria, fungi, and/or protozoa. These microorganisms act as "biocatalysts" to metabolize carbon based pollutants in an oxidative or aerobic process.
Aeration is generally carried out by injecting air under pressure into fluid to form bubbles or by allowing fluid to flow rapidly on and/or through surfaces or substrates to expose large surface areas of the fluids to air. Efficient and reliable aerating equipment is required to adequately aerate large volumes of fluids such as in a modern waste treatment plant. Current practice is to direct air into holding lagoons or tanks as bubbles so that they will pass upwards through the body of fluid and thereby oxidize any suspended organic matter.
This process is not entirely satisfactory since such aeration devices are often complex and rapidly become clogged due to suspended particulate material. Moreover, the mere presence of increased amounts of air will not always guarantee appropriate growth conditions for a particular type of microorganism. Nor does it assure that the microorganism will be present to utilize air flowing through a system. The time in which bubbles of air travel to the surface of a fluid body may be too brief to allow microorganisms to utilize the air resulting in inefficiencies.
Microorganisms obtain greater cell densities immobilized, as colonies, on solid surfaces. However, force which is created by the rapid discharge of bubbles from an air pump will often dislodge microorganisms attached to solid surfaces, thus defeating the intended purposes of the aeration.